Upload & Sell: On
On a few things..
First the AF speed on the 800 is way faster than the 100-400.
You get an indication of hat when shooting with the Mk4 when you lose drive speed at 10fps with the 100-400 attached particularly tracking targets.
The 100-400 is far easier to use due the the smaller viewing angle..tracking objects particularly small birds is far harder wih a long prime than a zoom where you can zoom out to locate then in to photograph. In that 40-80' range the 109-400 will be easier to use. The 800 is not designed to be used there.That is why when...Show more →
I think with aircraft photography you have a bit of a different situation......I think you can plan your shots better, and planes follow a fairly predictable trajectory in a linear fashion, and they are big.
Furthermore, I suspect you have your 800 focus limiter switch on 20m to infinity......in that range I also find that 800L focuses pretty good. Unfortunately, there are times with birds when they get within 20m and then I'd be screwed if I am on the long limiter setting. In order to remedy that, I turn the limiter switch to full range, i.e. 6m to infinity. That is a great range for slow and stationary targets, but for a rapidly evolving bird in flight I find it to be an unmitigated AF disaster.